The paper presents particle-based simulations of a dam break on a wet bed by standard and improved versions of three particle methods, namely, MPS, ISPH and WCSPH methods. The improved versions of the three mentioned methods are CMPS-HS, CISPH-HS and WCSPH-MLS methods. Direct comparisons of experimental photos and their corresponding simulation snapshots have been made in terms of the reproduced free-surface profile as well as the simulated mixing processes. In order to obtain further improved simulations, in this paper, we propose a new viscosity reduction function in WCSPH-MLS calculation, and apply a frictional force term in CMPS-HS method.